This invention relates generally to the providing or supplying of inflation gas and, more particularly, to the providing or supplying of such inflation gas via an elongated inflator such as may be desired for certain inflatable passive restraint systems for use in vehicles for restraining the movement of an occupant in the event of a vehicular collision.
It is well known to protect a vehicle occupant by means of safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e., “passive restraint systems.” Such systems commonly contain or include an inflatable vehicle occupant restraint or element, such as in the form of a cushion or bag, commonly referred to as an “airbag cushion.” In practice, such airbag cushions are typically designed to inflate or expand with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such airbag cushions may desirably deploy into one or more locations within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, instrument panel or the like, to prevent or avoid the occupant from forcibly striking such parts of the vehicle interior. For example, typical or customary vehicular airbag cushion installation locations have included in the steering wheel, in the dashboard on the passenger side of a car, along the roof line of a vehicle such as above a vehicle door, and in the vehicle seat such as in the case of a seat-mounted airbag cushion. Other airbag cushions such as in the form of knee bolsters and overhead airbags also operate to protect other or particular various parts of the body from collision.
In addition to an airbag cushion, inflatable passive restraint system installations also typically include a gas generator, also commonly referred to as an “inflator.” Upon actuation, such an inflator device desirably serves to provide an inflation fluid, typically in the form of a gas, used to inflate an associated airbag cushion. Various types or forms of inflator devices have been disclosed in the art for use in inflating an inflatable restraint system airbag cushion.
One particularly common type or form of inflator device used in inflatable passive restraint systems is commonly referred to as a pyrotechnic inflator. In such inflator devices, gas used in the inflation of an associated inflatable element is derived from the combustion of a pyrotechnic gas generating material.
Another known type of compressed gas inflator is commonly referred to as a “hybrid” inflator. In such an inflator device, inflation gas results from a combination of stored compressed gas and the combustion of a gas generating material, e.g., a pyrotechnic.
In view of possibly varying operating conditions and, in turn, possibly varying desired performance characteristics, there is a need and a desire to provide what has been termed an “adaptive” inflator device and a corresponding inflatable restraint system. With an adaptive inflator device, output parameters such as one or more of the quantity, supply, and rate of supply (e.g., mass flow rate) of inflation gas, for example, can be selectively and appropriately varied dependent on selected operating conditions such as ambient temperature, occupant presence, seat belt usage and rate of deceleration of the motor vehicle, for example.
While such adaptive systems are desirable, they typically require the inclusion of additional components as a part of the associated inflator device and such as may undesirably increase one or more of the size, cost and weight of the inflator device. For example, various proposed or available dual stage inflator devices appear based on the principle of packaging together two separate inflators. As a result, such inflator combinations commonly include two distinct pressure vessels, two sets of filter or inflation gas treatment components, one for the output of each of the pressure vessels, and two distinct diffusers, again one for the output of each of the pressure vessels. Thus, it has been difficult to provide an adaptive inflator which will satisfactorily meet the size, cost and weight limitations associated with modern vehicle design.
Upon actuation of the inflator device, inflation gas fills the inflatable cushion. Control over the size and shape of the inflated cushion can be provided through the use of tethering elements in the form of straps or webs extending between portions of the inflatable cushion and/or the inflatable cushion and the housing containing the inflatable cushion. The desired configuration of the inflated cushion may depend on the severity of the collision. In some instances, a tethered cushion may be desired, but in other instances no tethers may provide better protection. Release systems have been developed for releasing tethers upon one or more sensors determining particular collision parameters. However, such tether release systems generally require additional and relatively complex parts, thereby increasing the cost and difficulty of manufacture and installation of the inflatable cushion restraint system.
There is a need for an efficient and cost-effective adaptive inflator. There is also a need for a simple, efficient and cost-effective tether release system.